Technical Field of the Invention:
The present invention relates to photoprotective compositions comprising at least one 1,3,5-triazine compound dissolved within a mixture of at least one arylalkyl benzoate compound and at least one amide-based oil, and also to various cosmetic applications thereof, especially for protecting the skin and/or the lips and/or the integuments against the deleterious effects of ultraviolet radiation, in particular solar radiation.
Description of Background and/or Related and/or Prior Art:
It is known that light radiation with wavelengths of from 280 nm to 400 nm permits tanning of the human epidermis, and that rays with wavelengths of from 280 nm to 320 nm, known as UV-B rays, cause skin burns and erythema which may be harmful to the development of a natural tan; this UV-B radiation should thus be screened out.
It is also known that UV-A rays, with wavelengths of from 320 nm to 400 nm, which cause tanning of the skin, are liable to induce an adverse change therein, especially in the case of sensitive skin or of skin which is continually exposed to solar radiation. UV-A rays cause in particular a loss of elasticity of the skin and the appearance of wrinkles, leading to premature skin aging. Same promote triggering of the erythemal reaction or amplify this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. It is thus desirable also to screen out UV-A radiation.
Many cosmetic compositions intended for the photoprotection (UV-A and/or UV-B) of the skin have been proposed to date.
These antisun compositions are quite often in the form of emulsion of oil-in-water type (that is to say, a cosmetically acceptable support comprising a continuous aqueous dispersing phase and a discontinuous oily dispersed phase) which contains, in various concentrations, one or more conventional lipophilic and/or hydrophilic organic screening agents which are capable of selectively absorbing harmful UV radiation, these screening agents (and their amounts) being selected as a function of the desired sun protection factor, the sun protection factor (SPF) being expressed mathematically by the ratio of the UV radiation dose necessary to reach the erythema-forming threshold with the UV screening agent to the UV radiation dose necessary to reach the erythema-forming threshold without UV screening agent.
1,3,5-Triazine derivatives are particularly desired in antisun cosmetics due to the fact that they are highly active in the UV-B range, and even in the UV-A range for some of these compounds, depending on the nature of the substituents involved. Furthermore, they are photostable, i.e., they show little or no chemical degradation under the action of UV radiation. They are especially described in U.S. Pat. No. 4,367,390, EP-863,145, EP-517,104, EP-570,838, EP-796,851, EP-775,698, EP-878,469 and EP-933,376, and the following are known, in particular:                2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine or “Ethylhexyl Triazone” (INCI name), marketed under the trademark “Uvinul T 150” by BASF,        2-[(p-(tert-butylamido)anilino]-4,6-bis-[(p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine or “Diethylhexyl Butamido Triazone” (INCI name), marketed under the trademark “Uvasorb HEB” by Sigma 3V,        2,4-bis{[4-2-ethylhexyloxy)]-2-hydroxy]phenyl}-6-(4-methoxyphenyl)-1,3,5-triazine or “Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine” (INCI name), marketed under the trademark “Tinosorb S” by Ciba Specialty Chemicals.        
It has heretofore been proposed to include 1,3,5-triazine derivatives in oils such as esters and more particularly C12-C15 alkyl benzoates (“Finsolv TN” from Finetex), or triglycerides and especially C8-C12 fatty acid triglycerides (“Miglyol 812” from Hüls), or, alternatively, oxyethylenated or oxypropylenated fatty monoalcohols or polyols (“Cetiol HE” from Henkel or “Witconol AM” from Witco). The use of these oils presents two drawbacks:
(i) either the appearance over time of crystallization in the formulations, which is detrimental to the cosmetic qualities, the stability and the efficacy of antisun products; or
(ii) the limitation of the concentration of screening agents in the formulations, which does not make it possible to obtain products that are sufficiently effective.
The technical problem underlying the present invention is thus that of improving the photoprotective efficacy, the cosmetic properties and the stability of compositions containing such 1,3,5-triazine derivatives.
With this objective, it has already been proposed in EP-0-748,623 to add to 2,4,6-tris[p-(2′-ethylhexyl-1′-oxycarbonyl)anilino]-1,3,5-triazine or “Ethylhexyl Triazone” N,N-disubstituted amide-based compounds without emulsifying properties, for instance N,N-diethyl-3-methylbenzamide or ethyl N-butyl-N-acetylaminopropionate.
It has also been proposed in EP-1-269,980 to add to UV-screening agents of triazine type N-acyl esters of amino acids, for instance isopropyl N-lauroylsarcosinate.
The results obtained with these amide-based oils are still not entirely satisfactory.